U.S. patent application number 13/809227 was filed with the patent office on 2013-05-02 for converter material for solar cells.
This patent application is currently assigned to KONINKLIJKE PHILIPS ELECTRONICS N.V.. The applicant listed for this patent is Danielle Beelen, Nikolaos Christogiannis, Dirk Kornelis Gerhardus De Boer, Wilhelmus Cornelis Keur, Andries Meijerink, Cornelis Reinder Ronda. Invention is credited to Danielle Beelen, Nikolaos Christogiannis, Dirk Kornelis Gerhardus De Boer, Wilhelmus Cornelis Keur, Andries Meijerink, Cornelis Reinder Ronda.
Application Number | 20130105736 13/809227 |
Document ID | / |
Family ID | 44511111 |
Filed Date | 2013-05-02 |
United States Patent
Application |
20130105736 |
Kind Code |
A1 |
Ronda; Cornelis Reinder ; et
al. |
May 2, 2013 |
CONVERTER MATERIAL FOR SOLAR CELLS
Abstract
The invention relates to an converter material for solar cells
using Sm.sup.2+.
Inventors: |
Ronda; Cornelis Reinder;
(Aachen, DE) ; De Boer; Dirk Kornelis Gerhardus;
(Den Bosch, NL) ; Meijerink; Andries;
(Soesterberg, NL) ; Christogiannis; Nikolaos;
(Sheffield, GB) ; Beelen; Danielle; (Nederweert,
NL) ; Keur; Wilhelmus Cornelis; (Weert, NL) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Ronda; Cornelis Reinder
De Boer; Dirk Kornelis Gerhardus
Meijerink; Andries
Christogiannis; Nikolaos
Beelen; Danielle
Keur; Wilhelmus Cornelis |
Aachen
Den Bosch
Soesterberg
Sheffield
Nederweert
Weert |
|
DE
NL
NL
GB
NL
NL |
|
|
Assignee: |
KONINKLIJKE PHILIPS ELECTRONICS
N.V.
EINDHOVEN
NL
|
Family ID: |
44511111 |
Appl. No.: |
13/809227 |
Filed: |
July 5, 2011 |
PCT Filed: |
July 5, 2011 |
PCT NO: |
PCT/IB11/52972 |
371 Date: |
January 9, 2013 |
Current U.S.
Class: |
252/301.4R ;
977/773 |
Current CPC
Class: |
H01L 21/02521 20130101;
H01L 21/02581 20130101; B82Y 30/00 20130101; H01L 31/055 20130101;
Y02E 10/52 20130101; H01L 31/02322 20130101; Y10S 977/773 20130101;
H01L 21/02565 20130101 |
Class at
Publication: |
252/301.4R ;
977/773 |
International
Class: |
H01L 31/0232 20060101
H01L031/0232 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 13, 2010 |
EP |
10169389.3 |
Claims
1. Converter material for solar cells comprising a Sm.sup.2+ doped
inorganic material, whereby the converter material has a band gap
of .gtoreq.4.5 eV.
2. The converter material for solar cells of claim 1, whereby the
converter material for solar cells is selected from the group
comprising oxidic, nitridic, oxidonitridic, boridic, borate,
phosphate materials and mixtures thereof
3. The converter material for solar cells of claim 1, whereby the
converter material is selected from the group comprising alkaline
and/or earth alkaline containing materials.
4. (canceled)
5. The converter material for solar cells of claim 1 whereby the
emission of the converter material has a decay time of .gtoreq.50
.mu.s.
6. The converter material for solar cells of claim 1, whereby the
undoped material is a non-coloured material which is coloured when
doped with Sm.sup.2+.
7. The converter material for solar cells of claim 1, whereby the
converter material comprises an earth-alkaline borate.
8. (canceled)
9. Solar cell comprising a converter material according to claim
1.
10. Solar cell of claim 9, whereby the converter material is
provided in the form of nanoparticles.
Description
FIELD OF THE INVENTION
[0001] The present invention is directed to converter materials for
solar cells
BACKGROUND OF THE INVENTION
[0002] State of the art solar cells cannot achieve the theoretical
efficiency (as determined by the so-called "Shockley-Queisser"
limit) for various reasons. Therefore many attempts have been made
to increase the efficiency of Solar cells by either varying the
solar cell material or addition of further components etc.
Alternatively, the cost of solar cells can be reduced by the use of
solar energy concentrators. Both measures have the potential to
increase the use of solar cells as the costs per Wp decrease.
[0003] One strategy for the increase of solar cells is the
introduction of converter materials which (most desirably) have a
broadband absorption and line emission in desired wavelength areas.
However there are not many converter materials known and therefore
there is the constant need for alternative converter materials.
These materials are used in so-called luminescent solar energy
concentrators (LSC). Sunlight impinges on a large area, is
converted into light of longer wavelenght and subsequently guided
to photovoltaic elements. In this way the amount of expensive
photovoltaic material to be used can be reduced considerably.
SUMMARY OF THE INVENTION
[0004] It is an object of the present invention to provide a
converter material for solar cells which is able to decrease the
costs and to increase efficiency for the conversion of deep blue/UV
radiation of solar cells by a broadband absorption and line
emission in suitable wavelength areas.
[0005] This object is solved by a converter material for solar
cells according to claim 1 of the present invention. Accordingly,
an converter material for solar cells, is provided, comprising a
Sm.sup.2+ doped inorganic material
[0006] Surprisingly it has been found that such a converter
material for solar cells has for a wide range of applications
within the present invention at least one of the following
advantages: [0007] The materials comprising Sm.sup.2+ employ for
many applications a large Stokes shift, [0008] The efficiency is
increased as the conversion efficiency of solar cells is decreasing
rapidly below 400 nm. [0009] The costs of solar cells are decreased
when the inventive materials are used in solar cells, such as LSCs.
[0010] Furthermore many inventive materials show a broad tunable
absorption spectrum [0011] In most inventive materials line
emission can be observed which prevents reabsorption (forbidden
transitions) [0012] Furthermore it has been found that said line
emission is (almost) independent of the host lattice, enabling the
use of more than one luminescent material (to absorb as much
sunlight as possible) in combination with interference filters, to
keep the emission within the solar cell
[0013] Preferably the converter material for solar cells the
converter material for solar cells is selected from the group
comprising oxidic, nitridic, oxidonitridic, boridic, borate,
phosphate materials and mixtures thereof. These materials have been
found advantageous in practice. Additionally or alternatively
according to another embodiment of the present invention, the the
converter material is selected from the group comprising alkaline
and/or earth alkaline containing materials.
[0014] According to a preferred embodiment of the present
invention, the converter material has a band gap of .gtoreq.4.5 eV.
This has been advantageous for many applications since then it has
been found that in materials with too small a value for the
bandgap, the excited Sm.sup.2+ ions easily oxidise to Sm.sup.3+ and
this results in quenching of the emission. Preferably the converter
material has a band gap of .gtoreq.5 eV.
[0015] According to a preferred embodiment, the undoped material is
a non-coloured material which is coloured when doped with
Sm.sup.2+.
[0016] The term "non-coloured" especially means and/or includes
that the material has no absorption in the visible wavelength area
or an absorption of .ltoreq.10%, whereas the term "coloured" to the
contrary especially means and/or includes that the material has an
absorption and/or emission (preferably of larger than 50%) in the
visible wavelength area.
[0017] According to a preferred embodiment, the converter material
comprises an earth-alkaline borate, preferably a material of the
structure EA.sub.1-xB.sub.4O.sub.7:Sm.sub.x with EA being an earth
alkaline metal or mixtures of earth alkaline metals. Preferably EA
is Sr and/or Ba.
[0018] This material has shown in practice to be a very good
converter material as will be described later on.
[0019] The present invention furthermore relates to the use of
Sm.sup.2+ as absorber and/or emitter in converter materials for
solar cells
[0020] Furthermore the present invention relates to a solar cell
using an inventive material or making use of Sm.sup.2+ as absorber
and/or emitter in converter materials for solar cells.
[0021] Preferably the converter material is provided in said solar
cells in nanoparticle form, preferably with an average particle
size of .gtoreq.1 nm and .ltoreq.1 .mu.m, preferably .gtoreq.100 nm
and .ltoreq.500 nm, most preferred .gtoreq.50 nm and .ltoreq.100
nm. This is especially advantageous when the converter is present
in a light guide, as scattering losses are reduced in this way,
provided that the refractive indices (n) of the light guide and the
phosphor materials match (typically .DELTA.n<0.05).
[0022] Alternatively the the converter material is provided in said
solar cells in form of grains with with an average particle size of
.gtoreq.1 .mu.m, more preferred .gtoreq.5 .mu.m. This arrangement
is especially advantageous when the converting layer is positioned
under the light guide with respect to the direction of the
light.
[0023] The aforementioned components, as well as the claimed
components and the components to be used in accordance with the
invention in the described embodiments, are not subject to any
special exceptions with respect to their size, shape, material
selection and technical concept such that the selection criteria
known in the pertinent field can be applied without
limitations.
BRIEF DESCRIPTION OF THE DRAWINGS
[0024] Additional details, features, characteristics and advantages
of the object of the invention are disclosed in the subclaims, the
figures and the following description of the respective figures and
examples, which--in an exemplary fashion--show several embodiments
and examples of converter material for solar cellss according to
the invention.
[0025] FIG. 1 shows an emission spectrum of an inventive material
according to the present invention (Example I)
[0026] FIG. 2 shows the excitation spectrum of the material of FIG.
1
[0027] The invention will furthermore be understood by the
following Inventive Example which is merely for illustration of the
invention only and non- limiting.
EXAMPLE I
[0028] Example I refers to SrB.sub.4O.sub.7:Sm.sup.2+ which was
made the following way:
[0029] Stoichiometrically mixtures of Sm.sub.2O.sub.3, SrCO.sub.3,
H.sub.3BO.sub.3 (10% excess) were fired at 850.degree. C. for 20
hours in a reducing atmosphere (H.sub.2/N.sub.2). The samples were
checked by x-ray diffraction technique and their phase purity was
confirmed.
[0030] FIG. 1 shows the emission spectrum, FIG. 2 shows the
excitation spectrum of SrB.sub.4O.sub.7:Sm.sup.2+. It can clearly
be seen that this material is an excellent material of use in
converter material for solar cells due to the broadband absorption
of the material as well as the line emission together with a broad
Stokes shift.
[0031] The particular combinations of elements and features in the
above detailed embodiments are exemplary only; the interchanging
and substitution of these teachings with other teachings in this
and the patents/applications incorporated by reference are also
expressly contemplated. As those skilled in the art will recognize,
variations, modifications, and other implementations of what is
described herein can occur to those of ordinary skill in the art
without departing from the spirit and the scope of the invention as
claimed. Accordingly, the foregoing description is by way of
example only and is not intended as limiting. In the claims, the
word "comprising" does not exclude other elements or steps, and the
indefinite article "a" or "an" does not exclude a plurality. The
mere fact that certain measures are recited in mutually different
dependent claims does not indicate that a combination of these
measured cannot be used to advantage. The invention's scope is
defined in the following claims and the equivalents thereto.
Furthermore, reference signs used in the description and claims do
not limit the scope of the invention as claimed.
* * * * *